1. Field of the Invention
The present invention relates to an electronic control device for an aviation engine and particularly relates to an electronic control device for an aviation engine for automatically controlling all fuel consumption and ignition timing etc. using a computer.
2. Description of Background Art
FADEC (Full Authority Digital Engine Control) is a generic name for a system for electronically controlling an aviation engine, that receives information regarding the position of a throttle lever operated by a pilot and the engine, together with various information from various sensors fitted to the aviation craft, and controls the engine so as to obtain optimum engine thrust. Engine control is therefore electrical rather than mechanical as a result of adoption of FADEC, which enables improved responsiveness and accurate engine control. Further transmission of signals from the throttle lever in the cockpit to the engine are also changed to being electrical signals in a wire rather than carried out mechanically using cables as a result of the adoption of FADEC. This kind of FADEC is disclosed, for example, in U.S. Pat. No. 6,357,427 B1.
FIG. 4 is a block view of an ignition control system for a four cylinder aviation engine of the related art to which FADEC is applied, and shows a configuration where two ECU's 100 and 200 control two cylinders at a time independently. Each cylinder is equipped with main ignition plugs (1T to 4T) and back-up ignition plugs (1B to 4B) for backing these up.
At the first ECU 100, the main ignition plug 1T of the first cylinder and the back-up ignition plug 2B of the second cylinder are supplied with electricity by the simultaneous ignition type first ignition coil 21. The back-up ignition plug 1B of the first cylinder and the main ignition plug 2T of the second cylinder are supplied with electricity by the simultaneous ignition type second ignition coil 22. The first CPU 11 and second CPU 12 are connected via the first and second igniters 31 and 32 upstream of the first and second ignition coils 21, 22. The first and second CPU 11 and 12 acquire crank speed and cam timing via the sensor input interface 41 and control energizing of the ignition coils 21, 22 using ignition timing decided based on this information.
Similarly, at the second ECU 200, the main ignition plug 3T of the third cylinder and the back-up ignition plug 4B of the fourth cylinder are supplied with electricity by the simultaneous ignition type first ignition coil 23. The back-up ignition plug 3B of the third cylinder and the main ignition plug 4T of the fourth cylinder are supplied with electricity by the simultaneous ignition type fourth ignition coil 24. The third CPU 13 and fourth CPU 14 are connected via the third and fourth igniters 33 and 34 upstream of the third and fourth ignition coils 23, 24.
The third and fourth CPU 13 and 14 acquire crank speed and cam timing via the sensor input interface 42 and control energizing of the ignition coils 23, 24 using ignition timing decided based on this information.
According to this configuration, the main ignition plugs and the back-up ignition plugs are always ignited at all of the cylinders by each of the simultaneous ignition type ignition coils 21 to 24. This means that if one of the systems goes down at one ECU, this is compensated for by each cylinder of the other system firing. Namely, a redundancy function is implemented for the engine ignition.
FIG. 5 is a block view of a fuel injection system for a four cylinder aviation engine of the related art applied to FADEC, with the same numerals as before showing the same functions.
A normal injection signal line from the first CPU 11 is secured at the first injector 1J injecting fuel to within the first cylinder 1 via a high-side driver 51 with a current limiter. The normal injection signal outputted from the driver 51 is always monitored by the second CPU 12. Further, an alternate injection signal line from the second CPU 12 is secured at the first injector via a high side driver 56 with a current limiter.
Similarly, a normal injection signal line from the second CPU 12 is secured at the first injector 2J injecting fuel to within the first cylinder 2 via a high-side driver 52 with a current limiter. The normal injection signal outputted from the driver 52 is always monitored by the first CPU 121. Further, an alternate injection signal line from the first CPU 11 is secured at the second injector via a high side driver 55 with a current limiter.
Similarly, normal injection signal line from the third CPU 13 is secured at the third injector 3J injecting fuel to within the third cylinder 3 via a high-side driver 53 with a current limiter. The normal injection signal outputted from the driver 53 is always monitored by the fourth CPU 14. Further, an alternate injection signal line from the fourth CPU 14 is secured at the third injector via a high side driver 58 with a current limiter.
Similarly, normal injection signal line from the fourth CPU 14 is secured at the fourth injector 4J injecting fuel to within the fourth cylinder 4 via a high-side driver 54 with a current limiter. The normal injection signal outputted from the driver 54 is always monitored by the third CPU 13. Further, an alternate injection signal line from the third CPU 13 is secured at the fourth injector via a high side driver 57 with a current limiter.
In this configuration, each CPU calculates the amount of normal injection and the amount of alternate injection so that, for example, in the case of the first CPU 11, the amount for the normal injection for the first injector 1J and the amount for the alternate injection for the second injector 2J is calculated. In this way, if a normal injection signal is not outputted by the high side driver 52 with a current limiter even after a predetermined time elapses from the timing of the start of injection obtained from the alternate injection amount, it is determined that an abnormality has occurred at the normal injection system of the second injector 2J and an alternate injection signal is outputted.
The technology of the related art described above has the following technological problems.
(1) An expensive CPU is required for each of the cylinders.
(2) Each ECU only carries out control of two cylinder sections. This means that ignition control and fuel injection control for two cylinders is not possible when, for example, there is an accident such as damage or disengagement etc. of a connector for the sensor input interface.
(3) Each CPU operates independently. This means that in cases where complex ignition control such as lag angle control and advance angle control etc. is carried out taking not only crank and cam timing but also detection signals such as for an intake negative pressure sensor or nock sensor etc. as parameters, errors occur in the results of calculations of each CPU. As a result, in the case of ignition control, a shift occurs in the ignition timing of the main ignition plug and the ignition timing of the back-up ignition plug at each cylinder.
(4) The casing for the ECU is large for the type where an ignition coil is built into the ECU and restrictions on the fitting position are therefore substantial. When the ECU is fitted at a position away from the engine, the distance between the ignition coil and the ignition plug becomes substantial and the long high tension cable is therefore necessary. Because of this, not only is secondary energy loss in ignition substantial and a fall in voltage supplied to the ignition plug invited, but also influence on emission performance is substantial.